Phosphorothiolates having insecticidal properties, and method of making same



United States Patent PHOSPHOROTHIOLATES HAVING INSECTICIDAL PROPERTIES,AND METHOD OF MAKING SAME Harry W. Coover, Jr., and Joseph B. Dickey,Kingsport,

Tenn., assignors to Eastman Kodak Company, Rochester, N. Y., acorporation of New Jersey N0 Drawing. Application August 31, 1955,Serial No. 531,811

Claims. (Cl. 260-461) This application is a continuation-in-part of ourcopending application Serial No. 301,956, filed July 31, 1952.

This invention relates to certain new organo phosphorus compounds and toa method of preparing them. More particularly, this invention relates tocompounds resulting from reaction of perchloromethylmercaptan and atrialkyl or triaryl phosphite or sodium salt of a dialkyl or diarylhydrogen phosphite. The exact structure of the reaction product is notknown, however, the reaction probably takes place as follows:

ll 013G801 (Rom ouosPwRn RC1 01 C801 (RO)2P ONa. ClaCSl(OR)z NaCl Thecompounds obtained from the practice of our invention are particularlyvaluable as insecticides. They are also useful as intermediates in thesynthesis of other chemicals. They can be called 0,0-dialkyl ordiaryl-S-trichloromethyl phosphorothiolate.

We have found that perchloromethylmercaptan will react with a trialkylor triaryl phosphite or with the sodium salt of dialkyl or diarylhydrogen phosphite to produce hitherto unknown compounds havingunexpected insecticidal activity.

Accordingly it is an object of our invention to provide a new reactionas described above and to provide new compounds comprising the productsof this reaction.

The following examples will further illustrate the invention.

Example 1.0,0-diethyl-S-trichloromethyl phosphorothiolate Thirty-sevenand two tenths grams of perchloromethylmercaptan was slowly added to33.2 g. of triethylphosphite in a reaction flask equipped with astirrer, condenser and dropping funnel and cooled in an ice bath. Avigorous reaction took place as each drop was added. The rate ofaddition was controlled such that the reaction did not heat up aboveapproximately 10 C. After the addition was complete the reaction mixturewas allowed to warm up to room temperature. The ethyl chloride can beremoved from the reaction product by warming on a steam bath. Thecrudeproduct is sufiiciently pure for most uses. Purification of theproduct by distillation results in some loss due to decomposition. Thedistilled product had a boiling point of 68-73 C./1 mm.

Example 2.0,0-dibutyl-S-trichloromethyl phosphorothiolate Thirty-sevenand two tenths grams of perchloromethylmercaptan was slowly added to 50g. of tributylphosphite in a reaction flask equipped with a stirrer,condenser and dropping funnel. The reaction flask was cooled in an icebath. A vigorous reaction took place upon the addition of theperchloromethylmercaptan. The addition rate was controlled so that thetemperature did not exceed 10 C. After the addition was completed thereaction mixture was slowly heated to 100 C. Under this condition mostof the butyl chloride was removed and the remaining product issufiiciently pure for most uses. Purification of the product bydistillation results in some decomposition. The product distilled at98-103 C./ 1 mm.

Example 3 1 below 10 C. When theaddition was completed, the reactionmixture was heated at gentle reflux for one hour. The reaction mixturewas washed with water. The organic layer was fractionally distilled andthe product, B. P. 68-73 C./1 mm., collected.

Reaction products of other phosphites such as trimethyl, tripropyl,triphenyl, tritoluyl and the like, as well as the sodium salts of thecorresponding di-compounds can be readily prepared by reacting them withperchloromethylmercaptan under the same conditions thattributylphosphite was reacted.

UTILITY 0,0-diethyl-S-trichloromethyl phosphorothiolate in threedifferent series of tests of insecticidal powers was found, in 5%mixture with flour, to kill 100% of the flour beetles used in the testin each of the test periods of contact, these periods being in eachseries, 16 hours, 21 hours and 24 hours, respectively. A D. D. T.standard in the same concentration killed 20%, 35% and 50% of thebeetles in the same periods. Use of a blank specimen revealed 0%, 5% and5% of the beetles dead at the ends of the same periods. At 2%concentration, the 0,0-diethyl- S-trichloromethyl phosphorothiolatekilled from to in each of the three periods.

One microliter of a 1.0% solution of 0,0-'diethylS- trichloromethylphosphorothiolate in acetone was applied to the midthoracic point ofeach of 20 four-day-old female flies. After treatment they were placedin small cyclindical recovery cages and observed after 24 hours. Allflies were dead at the end of the 24-hour period.

An aqueous emulsion containing 0.1% 0,0-diethyl-S- trichloromethylphosphorothiolate was prepared. Two bean leaves which were heavilyinfested with both eggs and adult 2-spotted mites were dipped into thisaqueous emulsion and dried in a gentle air stream. These leaves werethen placed on damp paper toweling in Petri dishes. A 98% kill of theadult mites was observed after 24 hours. At the end of 1 week, a 67%kill of eggs was observed.

The test against adult mites was repeated at a concentration of 0.03%.At the end of 24 hours, an 83% kill of mites was observed.

We claim:

1. The process for preparing insecticidal compounds having the formulaClaCSP(O) (OR)2 comprising reacting perchloro methyl mercaptan with acompound of the formula where R is selected from the group consisting oflower alkyl, phenyl and toluyl and Y is selected from the groupconsisting of lower alkyl, phenyl, toluyl and sodium while maintainingthe temperature of the reaction mixture at approximately 10 C.

2. The process according to claim 1 where Y is lower alkyl.

3. The process according to claim 1 where Y is sodium.

4. The process for preparing a compound having the formulaCl3CSP(O)(OC2H5)2 comprising reacting perchloro methyl mercaptan withtriethyl phosphite at around 10 C.

5. The process for preparing a compound having the formulaC13CSP(O)(OC4H9)2 comprising reacting perchloro methyl mercaptan withtributyl phosphite at around 10 C.

6. The process for preparing a compound having the formulaCI3CSP(O)(OC2H5)2 comprising reacting perchloro methyl mercaptan withsodium diethyl hydrogen phosphite at around 10 C.

7. The process comprising reacting perchloro methyl mercaptan withtritoluyl phosphite at around 10 C.

8. As a composition of matter, compounds having the formula:

ClaCSP(O) (OR)2 4 wherein R is selected from the group consisting oflower alkyl, phenyl and toluyl.

9. As a composition of matter, the compound having the formula:

ClaCSP(O) (OC2H5)2 10. As a composition of matter, the compound havingthe formula:

Cl3CSP(O) (OC4H9)2 References Cited in the file of this patent UNITEDSTATES PATENTS 2,335,953 McCracken et a1. Dec. 7, 1943 2,690,450 Gilbertet a1 Sept. 28, 1954 2,690,451 Gilbert et a1 Sept. 28, 1954

1. THE PROCESS FOR PREPARING INSECTICIDAL COMPOUNDS HAVING THE FORMULACL3CSP(O)(OR)2 COMPRISING REACTING PERCHLORO METHYL MERCAPTAN WITH ACOMPOUND OF THE FORMULA